1. Field of the Invention
The present invention relates to an image display apparatus, and more particularly, to an image display apparatus for converting different kinds of analog image data received through one input unit into digital image signals through a plurality of analog to digital converters. The present application is based on Korean Patent Application No. 2002-2364, which is incorporated herein by reference.
2. Description of the Prior Art
A television will now be exemplified as an image display apparatus. In general, a television for decoding different kinds of image data has a picture in picture (PIP) function for displaying a main picture and a sub picture on one screen, or a double window function for displaying two images on one screen. The television receives a composite image signal and a component image signal through at least one decoder. Here, the decoder includes a plurality of analog to digital converters (ADC) for converting the composite image signal and the component image signal into digital signals.
FIG. 1 is a schematic block diagram illustrating the conventional television for reproducing different kinds of image signals. The conventional television includes: a decoder 11, a reproducing unit 13, a display unit 15 and a screen 17. The decoder 11 converts a composite signal, i.e., video burst synchronization (CVBS) signal, and a component signal, i.e., a luminance signal Y/chrominance signal C (Y/C) into digital signals. In addition, the decoder 11 designates a synchronization point for converting the digital CVBS, Y/C and RGB signals into original signals. The reproducing unit 13 recovers the original signals through the designated synchronization point of the CVBS, Y/C and RGB signals from the decoder 11, and optimizes the recovered CVBS, Y/C and RGB signals in a size displayed on the screen 17. The display unit 15 displays the CVBS, Y/C and RGB signals on the screen 17 in a size region having a size set up to display the CVBS, Y/C and RGB signals on the screen 17.
In general, the decoder 11 includes two switching units (not shown) for receiving the composite signal and the component signal, and switching and outputting the resultant signals, respectively. Here, the switching units receive different kinds of image signals. The switching unit for switching the composite signal and the component signal is connected to two ADCs (not shown), and the switching unit for switching the component signal is connected to four ADCs (not shown). Accordingly, the CVBS and the component signal, i.e., Y/C signals are converted into digital signals through the two ADCs, and the component signals other than Y/C, i.e., the RGB signals and a fast blanking (FB) signal inputted through a Scart jack of a European type television are converted into digital signals through the four ADCs.
When three signals including the CVBS and Y/C signals are inputted to the switching unit connected to the two ADCs, the switching unit converts the Y/C signals into one CVBS signal. Therefore, the switching unit transmits the two CVBS signals to the two ADCs, respectively, and the ADCs convert the CVBS signals into digital signals. However, when the Y/C signals are converted into one CVBS signal, image quality is reduced. Accordingly, when at least one input signal is the Y/C signal, the conventional television must convert the Y/C signal into one CVBS signal in order to convert the Y/C signal into a digital signal through the two ADCs. Moreover, since the Y/C signals are converted into one CVBS signal, the image quality of the signal is deteriorated.
Also, when a number of the ADCs for converting the two types of Y/C into a digital signal is increased to four, the cost of the product is increased.